Scarf stone (construction)
In the building industry is called schalstein or formwork an artificial stone, the one or more horizontal openings for the interior structural steel contains and vertical air chambers. The wall made of such stones is subsequently filled with concrete .
Scarf stones are mostly made of normal or lightweight concrete . But there are also scarf blocks made from insulating materials such as polystyrene . So these are only "stones" in form, not in substance. Such insulating blocks are used, for example, to build swimming pools. With the lightweight formwork blocks made of rigid polystyrene foam, very good insulation values can also be achieved, which means that buildings can even reach passive house level.
Usual heights are 17.5 cm, 20 cm to 25 cm, usual widths 10 cm, 15 cm, 20 cm, 24 cm, 25 cm, 30 cm, 40 cm, in Germany 17.5 cm, 20 cm, 24 cm, 30 cm, 36.5 cm, 42.5 cm, 49 cm. Depending on the width, approx. 67 to 278 liters of concrete are required per square meter of wall surface.
commitment
Formwork stones as a system of permanent formwork are laid dry (not mortared) and are often used for the construction of stable cellar walls. This avoids the costly construction of formwork, which is normally required for concreting, as well as shoring the very heavy foundation stones.
A further area of application is earthquake-prone areas in which the bond achieved by mortar between normal stones does not appear to be sufficient. It can also be used to secure terraces and embankments .
Scarf stones are the usual construction method in the Philippines .
